NB: In general, it's unclear what to do in cases
like the following one, even when sometimes
we could, indeed, prefer something:
```
fun foo(a: Int, b: String, c: Boolean)
fun foo(b: String, c: Boolean, a: Int)
foo(c = false, b = "", a = 0)
```
^KT-55933 Fixed
ProhibitAssigningSingleElementsToVarargsInNamedForm is enabled from 1.3
so there is no need to make FIR accepting single element passed through
named arguments.
In addition, we may want to report only
ASSIGNING_SINGLE_ELEMENT_TO_VARARG_IN_NAMED_FORM_FUNCTION and not arg
type mismatch. But FE1.0 is reporting both so I am following it. If we
want to remove the redundant report, we will probably want to remove
FirNamedVarargChecker and report during resolution as a cone diagnostic.
Nikolay Lunyak